Feeding Strategies in Teleost Fishes BIOE 127 Summer 2015 Vikram B. Baliga Ecology & Evolutionary Biology UC Santa Cruz Environment Characteristic Air Water Density 1.21 kg m-3 1.024 x 103 kg m-3 Dynamic Viscosity 18.08 x 10 -6 Pa*s 1.07 x 10 -3 Pa*s O2-Carrying Capacity 95% less than air Thermal Conductivity 23 x air Human Skull Fish Skull 44 bony elements at birth # of bones varies widely among species 22 bones as an adult Typically 30 to 60 bones Very little kinesis Highly kinetic Aquatic prey capture suction ram manipulation (biting) Liem, 1980 Steven Day Tim Higham Roi Holzmann Kristen Bishop Lepomis macrochirus DPIV Experiments DPIV: Flow Velocity Hydrodynamics of Suction Feeding (Day et al. 2005) I. Flow = symmetrical II. Velocity decreases drastically away from the mouth III. Fluid speed is only significant within 1 mouth diameter How Polypterus Conserved? Morphological Diversity Seahorses Mastacembalus Anguilla Catfishes Cichlids Three Major Feeding Categories in the Aquatic Environment 1) Inertial suction Not 2) Ram Feeding Mutually Exclusive 3) Manipulation Feeding Mechanisms Body Ram Suction Jaw Ram Jaw Ram Necessitates Jaw Protrusion Jaw Protrusion Extremes Why might jaw protrusion have evolved? 1. Sneak up on your prey 2. Increase forces exerted on your prey Research on Jaw Protrusion • Accelerates the water around the prey • Increase by up to 35% the total force exerted on attached, escaping and free-floating passive prey • the strike. Feeding Mechanisms Body Pure Ram Ram Suction Jaw Ram Pure Ram Strategy Feeding Mechanisms Body Pure Ram Ram Suction Jaw Ram Biting Extending the Strike Ram Biters Biting Diversity Model Jaw Closing 3rd order lever 0 1 Speed Force MA jaw –closing Needlefish 0.04 (Strongylura incisa) Gar 0.051 (Lepisosteus osseus) Barracuda 0.27 (Sphyraena barracuda) Queen trigger 0.43 (Balistes vetula) Summary Functional Roles of Suction 1. Respiration 2. Prey Capture 3. Prey Transport Gill Filaments 4,5 Prey Transport Mouth -> -> -> Branchial Arches -> oesophagus Sciaenops ocellatus -Red Drum Grubich and Westneat. 2006. Journal of Anatomy 1: 79-92 Pharyngeal Musculature Pharyngeal Jaw Epibranchial Pharyngobranchial ceratobranchial Pharyngeal Diversity (a) Papilliform –plant shredding (b) Molariform- crushing snails Snakes Mehta & Burghardt, 2008; Mehta 2009 Cundall &Greene, 2000 Elongate Limb-reduced Forms Teleost Phylogeny Anguilliforms Morays • ~ 200 species • Complete limb loss • Coral reefs Snakes Morays • Elongate & limbless • Can attain large sizes • Obligate predators/ Consume large prey whole • Affect local prey densities How do morays consume large prey whole in the aquatic environment? Moray Skull What consequences do these features have on feeding behavior? Can morays generate suction? Pressure Data • Muraena retifera • Micropterus salmoides kPa = -1 kPa = -8 Mehta, unpubl data. Biters use suction to transport prey Inertial Feeding Pharyngeal Jaws Halichoeres bivittatus Morphological & Functional Innovation Prey Transport Behavior Thank you UCLA HARVARD LABORATORIES Feeding Mechanisms Body Pure Ram Ram Suction Jaw Ram Biting .